Formation and Hydrogen Storage Properties of Dual-Cation (Li, Ca) Borohydride

Abstract

Lithium borohydride, LiBH 4 , possesses high hydrogen capacity, but cannot be used for hydrogen storage owing to the problematic H-exchange kinetics and thermodynamics. In the present study, we employed the Li + -Ca 2+ combination strategy to improve the de/rehydrogenation properties of LiBH 4 . Our study found that mechanically milling 1:1 LiBH 4 /Ca(BH 4 ) 2 mixture formed a dual-cation borohydride, Li 0.9 Ca(BH 4 ) 2.9 , which then transformed to stoichiometric LiCa(BH 4 ) 3 in the heating process. The formation and decomposition behaviors of LiCa(BH 4 ) 3 were studied using X-ray diffraction and thermogravimetry/differential scanning calorimetry/mass spectroscopy techniques. It was found that LiCa(BH 4 ) 3 differs significantly from the component phases in terms of physical properties, decomposition behaviors, and mechanistic pathway. In particular, LiCa(BH 4 ) 3 exhibits improved de/rehydrogenation properties relative to the component phases. These experimental findings exemplified the effectiveness of manipulation of dual-cation combination in tuning the de/rehydrogenation properties of the ionic light-metal borohydrides.

First-principles predicted low-energy structures of NaSc(BH4)4

“…At the room temperature T = 298 K, the reaction (2) was predicted 14,15 to occurs at the hydrogen pressure P H 2 from 10 3 to 10 7 bar. As the minimum hydrogen pressure P min H 2 = 10 3 bar was predicted for the Cmcm phase, this parameter can be estimated for other low-energy structures of NaSc(BH 4 ) 4 assuming that there is no change in the products of the reaction (2). Hence, the change of the Gibbs energy ∆G(T ) is given by the change in the Helmholtz free energies, calculated at the PBE level and shown in Table II.…”

Ionic conductivity and the formation of cubic CaH2 in the LiBH4–Ca(BH4)2 composite

“…Reports on the structure and hydrogen storage properties of the LiBH 4 -Ca(BH 4 ) 2 composite have been published [48,49]. Accounts of the nature of the LiBH 4 -Ca(BH 4 ) 2 mixtures differ, however, as Z. Fang et al reported on the formation of a dual-cation borohydride LiCa(BH 4 ) 3 , while J. Y. Lee et al concluded that LiBH 4 and Ca(BH 4 ) 2 coexist as a physical mixture but not as a compound or a solid solution.…”

Experimental and Computational Investigations of the Deactivation of H‐ZSM‐5 Zeolite by Coking in the Conversion of Ethanol into Hydrocarbons

“…Predicting suitable geometries that do not rely on dispersion interactions and making trend statements can be achieved at lower costs. [34][35][36][37] Therefore, as long as one stays away from calculating exact energies with a claim of chemical accuracy, one can reliably apply mainstream quantum chemical calculations to zeolite models to evaluate trends.…”